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METABOLISM, CELL RESPIRATION
& PHOTOSYNTHESIS TOPIC 8
8.1 – METABOLISM ........................................... 1 8.2 – CELL RESPIRATION ................................. 8 8.3 – PHOTOSYNTHESIS ................................ 18 SAMPLE QUESTIONS ..................................... 29
TOPIC 8 – METABOLISM, CELL RESPIRATION & PHOTOSYNTHESIS
1
8.1 – METABOLISM
ENZYME ACTION
• Metabolism:
• Metabolic pathways: consist of _______________ or _______________ of _______________-_______________ reactions.
• Activation energy: the _________________ _________________ of energy needed to _________________ a chemical reaction.
• _________________ _________________ the _________________ _________________ of the chemical reactions that they catalyse.
• Due to the _________________ with the
enzyme, the _________________ in the _________________ molecules are _________________ (less stable).
• This lowers the overall energy level of the substrate molecules.
• This reduces the energy required to _________________ the reaction.
2
ENZYME INHIBITORS
1
• Inhibitor:
_________________ that _________________ to an enzyme and ____________________ or _________________ the enzyme’s function.
• Enzyme inhibitors can be _________________ or _____________________________.
Competitive Inhibitors • inhibitor and substrate are
___________________________________________________ • inhibitor binds to the _________________ site • ___________________________________________________
3
ENZYME INHIBITORS
2
• Examples:
− the inhibition of folic acid synthesis in bacteria by sulfonamide Prontosil™ (an _________________)
− the inhibition of enzyme-catalysed synthesis of fumerate by oxaloacetate in the _________________
− Use of _________________ to compete with the aldehyde oxidase enzyme in the _________________-_____________________ (increases _________________ as a result of the _________________ of _________________, a good _________________ from drinking)
Non-Competitive Inhibitors • inhibitor and substrate are ___________________________________________________ • inhibitor binds at an _________________ site (_________________ to the active site) • _________________ the _________________ of the active site • ___________________________________________________ • Examples:
− _________________ inhibition of _________________ oxidase (an enzyme in cellular respiration).
− Use of __________________________ for controlling __________________________________
§ ACE inhibitors inhibit _________________ Converting Enzymes
§ They __________________ _______________________ ________________ due to _________________ in the blood vessels.
4
ENZYME INHIBITORS
3
• The higher the concentration of competitive inhibitors, the slower / faster the rate of reaction. • At higher substrate concentrations, the effect of a competitive / non-competitive inhibitor can
be overcome. It therefore has _____________________ on maximum rate of reaction. • Since a non-competitive inhibitor prevents the enzyme activity regardless of substrate
concentration, it always reduces / enhances the max rate of reaction.
• Watch this à http://www.lourdes-luengo.org/unidadesbio/proteinas/swf/enzimas.swf
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END-PRODUCT INHIBITION
1
• when the _________________ of a pathway acts as an _________________ of the
pathway • a form of ____________________________ inhibition • _________________ _________________ the shape of the _________________ site • _________________ a large _________________ of products
• Example: − End-product inhibition of the pathway that converts threonine to isoleucine.
− Isoleucine (Ile) is an ____________________________ that is used in the
_________________ of _________________. − It as a _________________, amino acid which is _________________ in humans,
meaning the body _________________________________________, and must be _________________ in our diet.
− There are a _________________ of reactions needed to convert threonine to isoleucine.
− It is regulated by _________________ _________________. − _________________ enzymes catalyze the steps in the pathway. − The end product of the pathway, _________________, acts as an
_________________ of the _________________ of the pathway, __________________________________.
− Isoleucine is an _________________ _________________ (non-competitive inhibitor) of the enzyme threonine deaminase.
− The pathway is then _________________ when isoleucine concentrations _________________.
− If the concentration of isoleucine later falls as a result of its _________________ in cell synthesis, isoleucine is _________________ from the threonine deaminase enzymes and the ______________________________________________.
6
END-PRODUCT INHIBITION
2
7
BIOINFORMATICS
CALCULATING & PLOTTING RATES OF REACTION
Developments in scientific research follow improvements in computing • Developments in bioinformatics, such as the interrogation of
databases, have facilitated research into metabolic pathways.
• Bioinformatics is an approach where _________________ _________________
_________________ can add info to a _________________ enabling other groups to search/use the database.
• Example: − Databases have been used to identify potential new
___________________________________________________ − Malaria is caused by the _________________
_________________ pathogen. − _________________ are used as a _________________,
as are humans. − There is _________________ _________________ to the current anti-malarial
drugs. − In one study, using bioinformatics, _________________ _________________
were screened against both the resistant and non-resistant pathogens. − _______ new chemicals that _________________ the _________________
normally _________________ by anti-malarial drugs were found. − 15 additional chemicals that _________________ to _________________
_________________ were also identified Ø can help with _________________ the pathogen
• Rate of reaction can be calculated using either of the following formulae:
Rate of Reaction (s-1) = 1 / time taken (s)
OR
Rate of Reaction (cm3s-1) = volume change / time taken • Complete relevant practice Qs beginning on Page 29.
8
8.2 – CELL RESPIRATION
MITOCHONDRIA
•
• Involves _____________________ • Involves _____________________ _____________________ (chains and cycles) • Involves _____________________________ _____________________ • Involves _____________________ • Phosphorylates ADP to _____________________
______________ + ______________ –> ______________ + ______________ • Respiration includes:
− _____________________ − __________________________________________ − __________________________________________ − _______________________________________________________ − _____________________
• If _____________________ is present, the reactions move to the mitochondria. • The _____________________ of the mitochondrion is _____________________ to the
_____________________ it performs. • You need to be able to _____________________ a diagram of a mitochondrion to show the
way its structure is adapted to its function.
9
MITOCHONDRIA
• Cristae: − form a _______________________________________________________________ − have _____________________ needed for the _____________________
__________________________________________ embedded in their membrane • Intermembrane space:
− small to allow _____________ to _____________________ and create a _____________________ _____________________
• Matrix: − _____________________ containing _____________________ needed for the
__________________________________________.
• __________________________________________: technique for getting _____________________ of ___________________________ _____________________ using electron micrographs
• Technique has been used to produce images of active mitochondria • http://www.sci.sdsu.edu/TFrey/MitoMovie.htm
10
OXIDATION & REDUCTION
a) Cell respiration involves different reactions that are known as _________________ reactions (ie. oxidation or reduction reactions)
b) Oxidation & reduction _________________ _________________ - as one reactant is _________________, the other is _________________.
c) Remember: OIL RIG a. Oxidation Is Loss (of electrons) b. Reduction Is Gain (of electrons)
d) Reduction reactions may include:
a. _________________ of _________________ b. _________________ of _________________ c. _________________ of _________________
e) Oxidation reactions may include: a. Loss of electrons b. Addition of oxygen c. Loss of hydrogen
f) Cell respiration involves the oxidation and reduction of _____________________________.
g) What are the electron carriers in cell respiration?
a. _________________ – Nicotinamide Adenine Dinucleotide NAD+ + 2H+ + 2e- ⇌ _________________
b. _________________ – Flavin Adenine Dinucleotide FAD+ + 2H+ + 2e- ⇌ _________________
11
THE ART OF CELLULAR RESPIRATION
⇓ FINAL PRODUCT GOES HERE ⇓
12
GLYCOLYSIS
• Glycolysis occurs ___________________________________________________________ • Occurs in the _________________ • One glucose molecule is converted into _________________ molecules. • _________________ molecules are used but ____________________________________,
so there is a _______________________________________________________________. • _________________ are converted into _________________ • You don’t need to remember the names of the intermediate compounds in glycolysis. • There are 4 main stages:
1. _____________________ − _____________________ are added to _____________________ − _____________________ molecules are needed to provide the phosphate groups − _____________________________________________________________________
_____________________________________________________________________
2. _____________________ − The 6C molecule (__________________________________________) is then split
into ____________ molecules (__________________________________________).
3. _____________________ − _____________________ atoms are removed from each 3C molecule
à ___________ accepts them − ______________________________________ are added to each molecule
_____________________ the _____________________ released
4. ___________________________ − _____________________ groups are _____________________ from each molecule
à passed to _____________________ − This forms two molecules of _____________________ and _____________________. − This is called __________________________________________________________.
13
GLYCOLYSIS
14
THE LINK REACTION
THE KREBS CYCLE
• After glycolysis, pyruvate _________________ to the _________________. • _________________ in the _________________ _________________ are used to:
− _________________ the pyruvate remove _________________ à _______ accepts it − _________________ the pyruvate remove _________________ à ______ is released
• This conversion is called __________________________________________. • The product of this is an __________________________________, which attaches to
__________________________________ to form _________________.
• Also known as the ________________________ Cycle • Happens in the __________________________________ • Yields _________________ • _______________________ but process is ________________________ • C and O from C6H12O6 are __________________________________ • _____ is left over
• The Krebs Cycle occurs in a number of stages:
1) _________________ − _______________________ from the link reaction joins to __________________ (C4),
forming _________________ (C6) − __________________________________ and _________________
2) _________________ − _________________ – ____________ is released from citrate (C6), leaving a 5-carbon
compound (C5) − _________________ – ____________ accepts 2 H atoms à ____________________
15
THE KREBS CYCLE
3) _________________ − _________________ – ____________ is released from the C5 compound à forms a
C4 compound (______________________) − _________________ – ____________ accepts 2 H atoms à ____________________
4) ____________________________________________________________________ − ATP is synthesised from ADP − two _________________ reactions:
Ø NAD+ + 2H à _________________
Ø FAD + 2H à _________________ Manga guide to Biochemistry à http://www.slideshare.net/dekar001/nostarchmangaguide
• One turn of the Krebs Cycle yields:
− _________________ − _________________ − _________________ − _________________ (by substrate level phosphorylation)
• Remember that there are _________________ of the Krebs cycle for each glucose molecule!!!
16
THE ELECTRON TRANSPORT CHAIN (ETC) • The reduced forms of NAD (___________) and FAD (__________) carry ____________
and _________________ to the ETC. • The ETC is in the _________________ – the folds of the _________________
mitochondrial membrane (IMM). • The Electron Transport Chain (ETC) is composed of _________________
_________________ _________________ in the _____________. • _________________ are removed from NADH or FADH2 and passed from one carrier to
another by a series of __________________________________.
• The transfer of electrons is _________________ to __________________________________.
• _________________ are pumped across the membrane to the __________________________________ _________________ by the _________________ released from the electrons.
• Results in a _____________________________ of _________________ in the space between the membranes
17
CHEMIOSMOSIS
CELLULAR RESPIRATION
• In chemiosmosis, _________________ _________________ through
___________________________ to generate ATP. • _________________ is _________________ to bind with the free protons to maintain the
__________________________________, resulting in the _________________ of _________________.
• This occurs in the _________________ of the mitochondrion.
Paradigm shift • The chemiosmotic theory led to a paradigm shift in the field of
bioenergetics.
• In 1961, Peter Mitchell, a British biochemist, proposed the chemiosmotic theory of ATP production.
• He received a Nobel prize for this work in 1978. • His ideas explained how ATP synthesis is coupled to electron transport and the movement of
protons. • His ideas were different to previous explanations, but after many years, the theory was
accepted.
• Thus the net production of energy from aerobic respiration from ONE glucose:
Stage ATP
Glycolysis 2 ATP used at the start 2 NADH + H
+ Substrate level phosphorylation
Link Reaction 2 NADH + H+
Krebs cycle Substrate level phosphorylation
6 NADH + H+
2FADH2
Net Yield of ATP
• Complete relevant practice Qs beginning on Page 31.
18
8.3 – PHOTOSYNTHESIS
CHLOROPLASTS
•
• Involves _________________ • Involves _________________ _________________ (chains and cycles) • Consists of both light-dependent and light-independent stages • _________________ _________________ for use in cellular respiration or storage
• ______________ + ______________ –> ______________ + ______________
• Photosynthesis includes: − Light _________________ reactions − Light _________________ reactions − _________________ − __________________________________ − _________________ cycle
1
• _________________ _________________ cells at the top surface of leaves contain
chloroplasts.
• The structure of the chloroplast is adapted to the function it performs. • You need to be able to annotate a diagram of a chloroplast to show the way its structure is
adapted to its function.
19
CHLOROPLASTS
2
• Chloroplasts are bordered by a __________________________________
• Grana: ß site of ___________________________________________________ − made from _________________ (_________________ of membrane-bound sacs) − provide a ____________________________________ for light absorption − linked to each other by __________________________________
20
CHLOROPLASTS
CHLOROPLASTS
3
• Thylakoid space:
− __________ to allow _________ to _________________ and create a _________________ _________________
• Stroma: ß site of ___________________________________________________
− _________________ inside choroplast − contains _________________ for the Calvin cycle − contains ________________________ and _________________________ − contains ___________________________ and ____________________________ as
chemical energy stores
6CO2 + 12H2O –SUNLIGHT–> C6H12O6 + 6O2 + 6H2O Photosynthesis consists of light-dependent and light-independent reactions.
• Chloroplasts are bordered by a __________________________________
Light-dependent reactions Light-independent reactions
• Occur in the ____________________________ _________________ of the thylakoids
• Involves _______________ of ______________ • Involves ________________________________
• Occur in the _________________ • Involves ________________________________ • Involves ________________________________ • Involves ___________________________
_________________
21
LIGHT-DEPENDENT REACTIONS
1
• Short ‘n sweet:
− _________________ of _________________ à releases enough energy to make _________________ molecules
− _________________ _________________ energy − _________________ molecules _________________ into 24 H+ and 6 O2
Ø H is kept for ___________________________________________________ Ø O is _________________ as _________________
− _________________ is reduced to _________________
• Chlorophyll absorbs light − light energy transfers energy to
_________________ in the _________________ molecule
− results in an _________________ electron − this is known as ______________________
• Chlorophyll is located in the
_________________ membrane • It is arranged in groups of
molecules called _________________.
• There are two photosystems: − Photosystem I − Photosystem II
1) Chlorophyll in __________________________________ absorbs light • this energy _________________ electrons in
the chlorophyll • the excited electron is _________________
_________________ a _________________ of __________________________________ in the __________________________________
22
LIGHT-DEPENDENT REACTIONS
2
2) _________________ of _________________ _________________ the lost _________________ from _________________ • _________________ molecules break
apart • ______________________________ is released • the _________________ can either:
− __________________________________ at the end of the pathway or
− be _________________ into the __________________________________
3) Excited electrons are _________________ through _________________ _________________ in _________________ _________________ • _________________ carrier acts as a __________________________________ • _________________ are pumped into the thylakoid interior
4) ___________________________________________________ • Excited elecrons from PSII are used to generate a _________________________________
(high H+ concentration gradient) • The hydrogen ions _________________ in the thylakoid _________________. • The protons _________________ back through __________________________________,
through _________________ • This _________________ (from ADP and Pi)
23
LIGHT-DEPENDENT REACTIONS
3
5) ___________________________________________________ • Excited elecrons from _________ are used to _________________ _________________ • Light energy is absorbed by PSI (and passed to _________________) • The excited electrons are used to __________________________________
(and H+) in the _________________. • The NADPH is _________________ for the light-independent reactions.
24
LIGHT-INDEPENDENT REACTIONS
1
Short ‘n sweet: • does not require light energy • _________________ _________________ from light-dependent reactions • H combines with C and O _________________ to _________________ • _________________ molecules are _________________ as a _________________ • process _________________ _________________ molecules ∴ overall = 18 ATP – 18 ATP = __________________________________
1) _________________ _________________ (C1 + C5 = C6 → C3 + C3) • _____________ enters the chloroplast by
_________________ • CO2 combines with _________________
_________________ (RuBP) • This is a _________________ reaction and requires a
_________________ enzyme called _________________ • This produces a ________ compound that immediately
splits to form __________ molecules of __________________________________ (3C)
2) _________________ _________________ • Glycerate 3-phosphate is _________________ to _________________
_________________ • This requires _________________ and _________ (from the light-dependent reactions).
25
LIGHT-INDEPENDENT REACTIONS
2
3) Carbohydrate synthesis • Triose phosphate molecules are used to
_________________ _________________ and _________________ _________________
• This requires ___________ • TWO triose phosphate molecules are joined
together to form _________________ _________________
• _________________ reactions join the glucose phosphate molecules together to form _________________
26
LIGHT-INDEPENDENT REACTIONS
27
CALVIN’S EXPERIMENT
• The experiments performed by Melvin Calvin explained the process that plants use to make
food. • He introduced _________________ _________________ _________________ into
_________________ and analysed where it could be found in the cells using _________________ _________________.
• The results of his experiments showed that carbon dioxide was converted to carbohydrates during the light-independent reactions of photosynthesis.
• Watch this à http://wps.prenhall.com/wps/media/objects/1109/1135896/8_3.html
• Calvin used _________________ algae in a glass “lollipop” vessel • The algae where given light, CO2 and hydrogen carbonate (with __________) • Then the carbon compounds were replaced with compounds containing
_________________ carbon (____________) • The algae were then _________________ and the carbon compounds were
_________________ by _________________. • The 14C compounds were identified by ________________________. • _________________ _________________ appeared after only ________. • After __________, the other intermediates and the _____________________ were present.
Developments in scientific research follow improvements in apparatus
Ø Sources of 14C and autoradiography enabled Calvin to elucidate the pathways of carbon fixation.
• Complete relevant practice Qs beginning on Page 32.
28
THE ART OF PHOTOSYNTHESIS
⇓ FINAL PRODUCT GOES HERE ⇓
29
SAMPLE QUESTIONS
METABOLISM
1
Q1 An investigation was carried out which measured the volume of carbon dioxide released
over time. Calculate the rate of reaction.
Q2 Which is correct for the non-competitive inhibition of enzymes?
Q3 Consider the metabolic pathway shown below.
If there is end-product inhibition, which product would inhibit which enzyme?
30
METABOLISM
2
Q4 Discuss factors that affect enzyme activity. [9]
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31
CELL RESPIRATION
Q1 During glycolysis, a hexose sugar is broken down to two pyruvate molecules. What is the correct sequence of stages?
A. Phosphorylation → oxidation → lysis B. Oxidation → phosphorylation → lysis C. Phosphorylation → lysis → oxidation D. Lysis → oxidation → phosphorylation
Q2 What is the role of NADH + H+ in aerobic cell respiration?
A. To transfer hydrogen to the electron transport chain B. To reduce intermediates in the Krebs cycle C. To accept electrons from the electron transport chain D. To combine with oxygen to produce water
Q3
a) Indicate two places where decarboxylation occurs. [1] .........................................................................................
b) Explain why the given places were selected. [1]
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Q4 Explain the link reaction that occurs between glycolysis and the Krebs cycle. [4]
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PHOTOSYNTHESIS
1
Q1 Label these structures: (extension: Could you calculate it’s magnification???)
Q2 Where are the light-dependent and light-independent reactions taking place in the diagram
below?
Q3 Where are the light-dependent and light-independent reactions taking place in the diagram
below? A. In the intermembrane space B. In the stroma C. On the inner membrane D. In the thylakoid space
33
PHOTOSYNTHESIS
2
Q4 Outline the light-dependent reactions of photosynthesis. [6]
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Q5 Explain how the light-independent reactions of photosynthesis rely on the light-dependent
reactions. [6]
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